1. Field of the Invention
The present invention relates generally to heat exchangers for motor vehicles and, more specifically, to a flat turbulator for a tube and method of making same for a heat exchanger in a motor vehicle.
2. Description of the Related Art
It is known to provide a tube for a heat exchanger such as an oil cooler in a motor vehicle. The tube typically carries a first fluid medium in contact with its interior while a second fluid medium contacts its exterior. Typically, the first fluid medium is oil and the second fluid medium is air. Where a temperature difference exists between the first and second fluid mediums, heat will be transferred between the two via heat conductive walls of the tube.
It is also known to provide corrugated fins or ribs in the interior of the tube to increase the surface area of conductive material available for heat transfer to cause turbulence of the fluid carried in the interior of the tube and to increase the burst strength of the tube. One known method of making such a tube is to physically insert a corrugated fin into the generally flattened tube after the tube has been manufactured. This is an extremely difficult process since the corrugated fin to be inserted into the tube is extremely thin and subject to deformation during the insertion process.
It is also known to produce a corrugated fin or turbulator by a stamping process. An example of such a turbulator is disclosed in U.S. Pat. No. 5,560,425. In this patent, the turbulator is made by stamping in a direction parallel to the fluid flow or strip direction of the turbulator and has corrugations in a direction perpendicular to the direction of the flow of the fluid or strip direction.
Although the above turbulators have worked well, they suffer from the disadvantage that the stamping process does not have a high production through put. Another disadvantage of these turbulators is that the turbulators are inserted after the tube is made. Therefore, there is a need in the art to provide a tube with a flat turbulator and method of making same for a heat exchanger of a motor vehicle that overcomes these disadvantages.
Accordingly, the present invention is a tube for a heat exchanger including a base, a top spaced from and opposing the base, a first side interposed between the base and the top along one side thereof, and a second side interposed between the base and the top along another side thereof. The base, top, first side and second side form a channel. The second side is triple hemmed such that ends of the base and the top are disposed within the channel.
Also, the present invention is a flat turbulator for a heat exchanger including a base extending laterally and longitudinally in a strip. The flat turbulator also includes a plurality of corrugations spaced laterally along the base and extending longitudinally and generally perpendicular to the base in an alternating manner. The corrugations are rolled in a direction parallel to a longitudinal axis of the strip.
Further, the present invention is a method of making a flat turbulator for a heat exchanger. The method includes the steps of providing a generally planar strip having a base extending laterally and longitudinally. The method also includes the step of forming a plurality of corrugations spaced laterally along said base and extending generally perpendicular to said base in an alternating manner such that the corrugations extend in a direction parallel to a longitudinal axis of the strip.
Additionally, the present invention is a method of making a tube for a heat exchanger. The method includes the steps of providing a planar sheet having a generally planar base and a pair of terminal ends along a longitudinal length thereof and folding each of the terminal ends of the sheet to form a triple hem flange. The method includes the step of folding each of the terminal ends of the sheet toward one another until they meet to form a base, a top opposing the base, a first side interposed between the top and base and a second side interposed between said base to form a channel with free ends of the triple hem flange on each terminal end being disposed in the channel.
One advantage of the present invention is that a tube with a flat turbulator for a heat exchanger such as an oil cooler is provided for a motor vehicle for cooling liquid oil. Another advantage of the present invention is that the tube with the flat turbulator tube is more economical to manufacture with precise dimensional control. Yet another advantage of the present invention is that the tube is triple-hemmed to provide extra strength. Still another advantage of the present invention is that a method of making a flat turbulator is provided along with a method of making a tube with the flat turbulator. A further advantage of the present invention is that the method of making the flat turbulator uses roll forming to increase production through put. Yet a further advantage of the present invention is that the method of making the flat turbulator has the direction of roll forming the same as the strip or fluid direction such that the corrugations are perpendicular to the strip direction.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.